Over the past decade, thermoplastics have been used as alternative substrates to glass and Si for microfluidic devices because of the diverse and robust fabrication protocols available for thermoplastics that can generate high production rates of the desired structures at low cost and with high replication fidelity, the extensive array of physiochemical properties they possess, and the simple surface activation strategies that can be employed to tune their surface chemistry appropriate for the intended application. While the advantages of polymer microfluidics are currently being realized, the evolution of thermoplastic-based nanofluidic devices is fraught with challenges. One challenge is assembly of the device, which consists of sealing a cover plate to the patterned fluidic substrate.
Typically, channel collapse or substrate dissolution occurs during assembly, making the device inoperable resulting in low process yield rates. Now, in an article published in Lab on a Chip as a "Hot Article," researchers in the Soper Group report a low temperature hybrid assembly approach for the generation of functional thermoplastic nanofluidic devices with high process yield rates, >90%, and with a short total assembly time of only sixteen minutes. The functionality of the assembled devices was demonstrated by studying the stretching and translocation dynamics of dsDNA in the enclosed thermoplastic nanofluidic channels.
The phenomenon of ion pairing in aqueous solutions is of widespread importance in chemistry and physics, and charge transfer between the ions is fundamental to understanding the behavior of aqueous ionic solutions. At the same time, it is of significant challenge to describe the charge transfer behavior using popular density functional theory, DFT, calculations in practice because of approximated exchange-correlation effects of electrons.
In work published as a Frontiers Article and also as the cover article in Chemical Physics Letter, the group of Professor Yosuke Kanai shows how advanced quantum Monte Carlo, QMC, calculation is used to accurately quantify the charge transfer behavior in the NaCl dimer. Accurate electron density is obtained from the so-called reptation Monte Carlo approach, and influence of fermion nodes of the many-body wavefunction on the charge transfer behavior was discussed in detail. It is anticipated that the QMC approach will be of great importance for investigating a wide range of the charge transfer phenomena for which present-day DFT calculations are not reliable.